Isomerization process and catalyst



United States Patent ice 3,235,617 ISOMERIZATION PROCESS AND CATALYST v John Happel, Hastings on Hudson, Charles J. Marsel,

Flushing, and Joachim H. Blanck, Bronx, N.Y., assignors, by mesne assignments, to National Lead Company,

New York, N.Y., a corporation of New Jersey No Drawing. Filed Oct. 2, 1962, Ser. No. 227,708

14 Claims. (Cl. 260-678) This invention relates to a process for the vapor phase isomerization of allene to methyl acetylene, and more particularly to a catalytic process for effecting such isomerization, to the catalyst employed therefor and to the method of preparing the same. I

In the following specification the term conversion is intended to refer to the number of moles of allene reacted per mole of allene fed, the term selectivity to the moles of methyl acetylene produced per mole of allene reacted, and the term yield to the moles of methyl acetylene produced per mole of allene fed.

It is known to isomen'ze allene to methyl acetylene by contacting the former in the vapor phase and at elevated temperature with a silica-alumina catalyst activated with fluorine, hydrogen fluoride or other inorganic fluoride. This procedure is subject to the ditficulties inherent in handling the various toxic and corrosive fluoride materials including HF It is among the objects of the present invention to provide a relatively simple process for isomerizing allene to methyl acetylene which provides improved yields of methyl acetylene product, which secures increased catalyst life and which does not necessitate the use of highly corrosive and toxic catalyst activators.

It is a further object of the invention to provide a highly active catalyst useful in the practice of such process, which possesses a long life and which may be readily reactivated,

Another object of the invention is to provide an efiicient process for the preparation of such activated allene isomerization catalyst.

Other objects and advantages of the present invention will be apparent from the following detailed description thereof.

In accordance with the invention, a process for the isomerization of allene to methyl acetylene is provided, which involves contacting allene in the vapor phase at a temperature of from about 150 to about 410 C. with an alumina catalyst activated with a halocarbon activator having the formula C H X wherein X is a chloro, bromo or iodo radical, n is one or two, y is an integer from zen?) to five and z is an integer from one to six.

The activated alumina catalyst employed in the isomerization process is prepared by contacting an alumina catalyst with the aforesaid halocarbon at a temperature sufliciently high to cause the halocarbon to decompose on contacting the alumina catalyst particles. In this manner an activated isomerization catalyst is produced having a relatively long catalyst life, which may be readily reactivated by further treatment with the halocarbon activator. Moreover, the use of the thus resulting activated catalyst provides relatively high yields of the methyl acetylene and conversion of the allene reacted.

The alumina catalyst to be activated need not be specially prepared or highly purified activated alumina. It has been found that commercially available activated aluminas provide highly active catalysts for allene isomerization.

Preferred halocarbon activators include methyl iodide, methyl bromide, methyl chloride, chloroform, bromoform, carbon tetrachloride and ethylene dichloride. While the activating temperature required to decompose 3,235,617 Patented Feb. 15, 1966 the halocarbon employed depends upon the particular halocarbon, it has been found that, employing the above compounds, activating temperatures of from about 350 to about 850 C. are suitable. The activation treatment is preferably continued until free chlorine, bromine or iodine is recovered from the gaseous eflluent from the activation reaction mixture, although shorter activating periods can produce catalysts having sufficiently high isomerization activities. It has been found that generally from about 1 to 20 minutes are required to effect activation of alumina catalysts with the above typical halocarbon activators at the indicated activation temperatures.

In a preferred embodiment of the invention, a catalyst chamber is initially loaded with granular or pelleted alumina admixed with an inert heat stabilizing material such as quartz. Other inert, solid diluents which may be used in place of quartz include, for example, porcelain, corundum, and the like. In the absence of such an inert diluent, undesirable cracking of the hydrocarbon feed tends to occur. The catalyst is then activated by passing the aforesaid halocarbon activator over it at a temperature suflicient to decompose the halocarbon. The activator is admitted, in the case of gases, under its own cylinder pressure ,either alone or diluted with an inert gas such as nitrogen. Liquid activators are admitted to the catalyst chamber by bubbling an inert gas through them, the resulting vapor mixture being carried into contact with the heated alumina catalyst.

A similar technique is employed to reactivate an alumina catalyst after it has become deactivated through extended or improper use. The reactivation is carried out as a separate cycle in the manner described above, or it may be part of a regeneration cycle during which air or other oxidizing vapor is fed into the catalyst chamber to decarbonize the catalyst. When reactivated in the latter manner, the halocarbon activator is fed to the catalyst chamber alone, or in admixture with the regenerating gases, the temperature of regeneration usually being sufficient to effect decomposition of the halocarbon in the presence of the alumina catalyst, If necessary, 'heat is added to effect decomposition of the activator.

The isomerization may be carried out with a feed stock of pure allene or with a feed stock containing allene in addition to other low molecular weight hydrocarbons, such as may be present in reaction mixtures formed durmg the production of allene. The activated catalyst, prepared in accordance with the invention as described above, is contacted with the vaporous feed stock at a temperature of from about to about 410 C. It has been found that, when the isomerization is carried out at temperatures below about 150 C. relatively little conversion of the allene occurs, whereas when temperatures above about 410 C. are employed, the conversion is substantially complete but results in the production of contaminated end products. Preferably, the isomerization reaction is carried out at temperatures of from about 200 to about 400 C., at which the most satisfactory results have been obtained. The isomerization is ordinarily carried out at about atmospheric pressure.

The gaseous isomerization reaction mixture is caused to flow over the catalyst at a space velocity preferably ranging from 50 volumes of vapor flowed per hour per volume of catalyst space, to about 1000 volumes of vapor flowed per hour per volume of catalyst space, measured at S.T.P. (0 C., one atmosphere pressure). The space velocities utilized vary directly with the temperature of the reaction, the higher space velocities wtihin the indicated range being employed at the higher isomerization reaction temperatures.

The following examples illustrate specific embodiments of the allene isomerization process employing the aforesaid halocarbon activated catalysts in accordance with the present invention; it will be understood the examples are given for illustrative purposes and that the invention is not limited thereto.

A mixture of equal parts, by volume, 42.4 grams of activated alumina granules (commercial grade F-lO, Aluminum Corp. of America) and 68.9 grams of quartz chips was prepared in each of the following examples. 100 cc. of each mixture thus produced was loaded into a catalyst chamber and heated to a temperature sufiicient to decompose the halocarbon activator thereafter added thereto. Gaseous activators Were fed to the catalyst chamber under their own pressures, and liquid activators were fed in nitrogen streams bubbled therethrough. The activating procedure was carried out for a minute period at atmospheric pressure.

Thereafter, allene was passed over the resulting activated catalyst at atmospheric pressure and methyl acetylene thereby produced. The following table identifies the activated catalyst employed, the temperature of the activation, the isomerization reaction conditions and the production of methyl acetylene therefrom in each of a series of runs.

When the activated catalysts employed in the above examples were reacted with allene at temperatures of 410 C. or above total decomposition of the allene was eifected but the selectivity and yield of methyl acetylene were negligible.

The present invention thus provides a process for isomerizing allene, an activated catalyst useful therefor and a method of preparing such catalyst, which provides relatively high yields of methyl acetylene, and which process does not entail handling of toxic or corrosive catalyst activators.

Since certain changes may be made in the above methods and catalyst compositions without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A process for the isomerization of allene to methyl acetylene, which comprises contacting allene in the vapor phase at a temperature of from 150 to 410 C. with an alumina catalyst activated by decomposing a halocarbon having the formula C H X wherein X is selected from the group consisting of Cl, Br and I, n is an integer from one to two, y is an integer from zero to five and z is an integer from one to six, in the presence of said alumina catalyst.

2. The process as defined in claim 1, in which the isomerization reaction is carried out at a temperature of from 200 to 400 C. and the reaction vapors are flowed over the activated catalyst at a space velocity of from 50 to 1,000 volumes of vapor per hour per volume of catalyst space.

3. The process as defined in claim 1, in which the halocarbon is a compound selected from the group consisting of methyl iodide, methyl bromide, methyl chloride, chloroform, bromoform, carbon tetrachloride and ethylene dichloride.

4. The process as defined in claim 1, in which the halocarbon is methyl chloride.

5. The process as defined in claim 1, in which the halocarbon is methyl iodide.

6. The process as defined in claim 1, in which the halocarbon is methyl bromide.

7. The process as defined in claim 1, in which the halo carbon is carbon tetrachloride.

8. In a cyclic vapor phase process for the isomerization of allene to methyl acetylene, which comprises the steps of contacting allene in the vapor phase at a temperature of from to 410 C. with an activated alumina catalyst, regenerating the alumina catalyst to remove carbonaceous material therefrom and periodically reactivating the alumina catalyst, the improvement comprising activating and reactivating the catalyst by decomposing a halocarbon having the formula C H X wherein X is selected from the group consisting of Cl, Br and I, n is an integer from one to two, y is an integer from zero to five and z is an integer from one to six, at a temperature of from 350 to 850 C., in the presence of said alumina catalyst.

9. A method of preparing an activated alumina catalyst for the isomerization of allene to methyl acetylene which comprises contacting the alumina catalyst with a halocarbon having the formula C H X wherein X is selected from the group consisting of Cl, Br and I, n is an integer from one to two, y is an integer from zero to five and z is an integer from one to six, at a temperature sufiicient to decompose said halocarbon.

10. The method as defined in claim 9, in which the alumina catalyst and said halocarbon are contacted at a temperature of from 350 to 850? C.

11. The method as defined in claim 10, in which said halocarbon is selected from the group consisting of methyl iodide, methyl bromide, methyl chloride, chloroform, bromoform, carbon tetrachloride and ethylene dichloride.

12. A catalyst for the isomerization of allene tomethyl acetylene, prepared in accordance with claim 9.

13. A catalyst for the isomerization of allene to methyl acetylene prepared in accordance with claim 10.

14. A catalyst for the isomerization of allene to methyl acetylene prepared in accordance with claim 11.

References Cited by the Examiner UNITED STATES PATENTS ALPHONSO D. SULLIVAN, Primary Examiner. 

1. A PROCESS FOR THE ISOMERIZATION OF ALLENE TO METHYL ACETYLENE, WHICH COMPRISES CONTACTING ALLENE IN THE VAPOR PHASE AT A TEMPERATURE OF FROM 150* TO 410*C. WITH AN ALUMINA CATALYST ACTIVATED BY DECOMPOSING A HALOCARBON HAVING THE FORMULA CNHYXZ, WHEREIN X IS SELECTED FROM THE GROUP CONSISTING OF C1, BR AND I, N IS AN INTEGER FROM ONE TO TWO, Y IS AN INTEGER FROM ZERO TO FIVE AND Z IS AN INTEGER FROM ONE TO SIX, IN THE PRESENCE OF SAID ALUMINA CATALYST. 